The objectives of this study are: (1) to evaluate various parameters of hemolysis as to their usefulness in measuring hemolytic rate in patients with cardiac hemolytic anemia; (2) to determine the state of iron balance in these patients when on therapeutic doses of oral iron; and (3) to seek ways to minimize the rate of hemolysis in patients with cardiac lesions, or prosthetic valves. Patients currently followed by the Hematology Branch will be re- evaluated periodically, in an effort to identify factors responsible for the inadequate bone marrow response to hemolysis. Additional patients will be studied to define further the relationship between hemolytic rate, degree of anemia, and bone marrow function.